[HN Gopher] Ultra-low-power localization tag uses cellular signa...
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Ultra-low-power localization tag uses cellular signals [pdf]
Author : nakulgarg22
Score : 37 points
Date : 2024-12-12 19:25 UTC (3 hours ago)
(HTM) web link (www.cs.umd.edu)
(TXT) w3m dump (www.cs.umd.edu)
| anonu wrote:
| I had 2 questions: 1. what about data transmissions 2. what about
| using this on containers in the open seas?
|
| The first questions is at least partly answered in the document,
| copied below. However, you still need a collection infrastructure
| to make this useful.
|
| > Communicating locations: Localization trackers often need a
| communication module to periodically update location to a server
| or nearby hub. Standalone GPS trackers (e.g., [35] and [95])
| often use cellular or satellite communications to do so. LiTEfoot
| can incorporate an NB-IoT module for relaying location data.
| Using a low-power NB-IoT transmitter [96], which consumes 76 mW
| to transmit a 140 kb packet in eDRX mode, the system can
| intermittently send updates hourly, daily, or monthly depending
| on the application. This enables LiTEfoot to operate for
| approximately 10 years on a coin cell. The same antenna frontend
| can be shared between LiTEfoot and the communication unit,
| maintaining a compact form factor while providing flexible
| communication capabilities.
| davidhyde wrote:
| There are many cheap ultra low power microcontrollers that can
| keep a time clock going and a small amount (say 32KB) of ram.
| 30 years on a coin cell. Pair that with a Bluetooth low energy
| transceiver to automatically transfer the data when the home
| base is in range (or any number of base stations). Like at a
| port in your example.
| micw wrote:
| Cool. I want this for my cats, my kids, my keys and everything
| else.
|
| But I wonder: if millions of this are deployed, would this weaken
| cellular signals (by drawing power from it)?
| timerol wrote:
| Do you currently have tracker tags on those things? If not, why
| not? Multi-year lifetimes are already available with Tile (3
| years), AirTag (>1 year), and Samsung's SmartTag 2 (700 days),
| using BLE detection instead of 4G detection.
|
| Millions of these would not degrade signal. A random bit of
| metal (like a quarter, as shown for scale) in between you an a
| 4G tower should have the same effect as one of these devices.
| They are detecting existing 4G signal, not using it for energy
| harvesting.
| micw wrote:
| Thanks. I miss-read it and thought it's energy harvesting
| from celular.
|
| I already have some trackers on important stuff (like keys
| and school bag of kids if they loose it in the bus). But for
| other use cases it's either too large (cats) or makes no
| sense to have too many because then I'd have to replace a
| battery every few weeks ("everything else").
| dylan604 wrote:
| > replace a battery every few weeks
|
| make it easy on yourself and change them all on the same
| day like a clock reset day like the recommendation for your
| smoke detectors. bite the bullet and change change some
| early to get them on the same schedule. it's worth it for
| sanity
| dylan604 wrote:
| > Do you currently have tracker tags on those things?
|
| Yes. I have AirTags on my fur babbies, but if I were to need
| to use them I'd be hoping they came within range of a device
| to pick them up. Then, in FindMy app, I could see where the
| had been, but not where they are now to go get them. I would
| hope a system like this could give me a much more current
| location. Hopefully, I'll never need any of this.
| fellerts wrote:
| How are they able to achieve sub-100 meter accuracy? I might be
| missing something, but In my experience, collecting the cellular
| parameters is the easy part. The challenge is knowing where the
| cells actually are. You can ask Google's geolocation API, but
| that typically returns a fix with ~1000 meter accuracy if it
| returns a fix at all. These databases are curated based on
| GPS+cellular information from millions of phones. There is no
| global source of truth.
|
| If only base stations included location information in their
| transmissions...
| timerol wrote:
| FTA: Our localization approach combines open-source databases
| (OpenCellID [47], Mozilla Location Services [66], and
| CellMapper [12]) for PCI-to-coordinate mapping of cell towers
| with a trilateration technique based on relative signal
| strengths.
| ssl-3 wrote:
| Interesting.
|
| CellMapper, at least, is not even a little bit open source.
| It doesn't even have an API.
|
| This leads me to wonder what other details that FA provides
| which might have been fabricated from thin air.
| gbru-ty wrote:
| If someone is focusing on extracting data for a small area,
| they can manually browse the CellMapper data. An API isn't
| required for that--it's a matter of accessing and analyzing
| what's already available through the platform.
| gruez wrote:
| That doesn't really answer the question. Those services
| basically work the same way as Google's geolocation API, but
| they're somehow able to magically get better accuracy.
| timerol wrote:
| The coolest hack in here is definitely the way that the 4G base
| station can be (mostly uniquely) identified after the RF signal
| for a packet is run through an envelope detector through a low-
| pass filter, as opposed to the normal (and higher-power) method
| of using a high-frequency oscillator and a demodulation chain.
| phoronixrly wrote:
| Relevant Don't Get Distracted (2017)
| https://news.ycombinator.com/item?id=42388354
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